Can UCC24630 or UCC24636 be used as Synchronous rectifier controller for LLC?

The answer:
No they cannot. They are using Volt-Sec method for determining turn off of SR FET and they are designed specifically for single-ended supplies like flyback (or ground-reference freewheeling diode in a forward: e2e.ti.com/.../480940).

You can however use an SR controller like UCC24610 to achieve this as it uses Vds sensing for control method. Depending on what the output voltage is though you may need a separate bias for UCC24610 as it's limited to 5V.
See these design references:
e2e.ti.com/.../powerlab-notes-how-to-implement-synchronous-rectifiers-in-a-resonant-llc-half-bridge
e2e.ti.com/.../1573408
Digital Control LLC SR: www.power-eetimes.com/.../llc-synchronous-rectification-made-easy-robust-and-more-efficient.html
Digital Control LLC SR controller companion to UCD3138: www.ti.com/.../datasheet

Regards,
John